The present invention relates to fluid dispensers, and more particularly to comestible fluid dispensing taps and methods of dispensing comestible fluid from such taps.
A large number of comestible fluid dispensing systems and taps exist, most of which are adapted to dispense a particular type of comestible fluid. For example, some systems and taps are well-suited for dispensing relatively low-viscosity comestible fluids such as beer, soda, and other beverages, while other systems and taps are designed for dispensing more viscous comestible fluids such as ketchup, mustard, relish, mayonnaise, and other condiments. These latter comestible fluids often present unique problems for condiment dispensing systems and taps due to their higher viscosity. For example, relatively viscous condiments hang from a tap after dispense. This not only presents an unappealing appearance to later users of the tap, but also increases the chance that the dangling condiment will spoil before being used. Either result can significantly lower the desirability of the condiment and can therefore negatively impact condiment sales. Although the chances for hanging condiment is greater with higher viscosity fluids, the problems just described are relevant for virtually every comestible fluid (and are addressed by the present invention as described below).
Conventional comestible fluid dispensing systems and taps also address comestible fluid drip problems in varying ways and with varying success. Comestible fluid dripping between dispenses is undesirable for obvious reasons, and can be dependent upon the type of comestible fluid being dispensed.
A number of conventional devices and methods exist for addressing dangling comestible fluid and dripping problems described above. For example, the condiment dispensing system disclosed in U.S. Pat. No. 5,624,056 issued to Martindale employs a movable valve element which swipes the nozzle of the tap to remove excess condiment therefrom. In U.S. Pat. Nos. 6,082,587 and 5,906,266 issued to Martindale et al., a valve is used to reverse condiment flow at the end of condiment dispense to pull condiment on the nozzle back into the nozzle.
Conventional devices and method used for preventing comestible fluid buildup, dangling, and drips on a tap nozzle have a number of significant limitations. Typically, such devices and methods only partially protect against comestible fluid spoilage because comestible fluid that has exited the tap or nozzle is often still partially or fully exposed to the outside environment (although not always visible to a user). Also, such devices and methods employ relatively complex mechanisms for performing their tasks to prevent comestible fluid buildup, dangling, and drips. These mechanisms can therefore can be expensive to manufacture, assemble, and maintain, thereby adding to dispensing system and tap cost.
As mentioned above, some conventional devices and systems employ a drawback valve to draw comestible fluid back into the tap or nozzle after a dispense. A problem with such devices and systems is that the draw-back valve adds yet another component to the comestible fluid dispenser, requiring additional comestible fluid lines and connections, significantly adding to the total cost of the dispenser, and increasing system complexity. Furthermore, the draw-back valve in these dispensers is a separate device located a distance from the tap and connected to the tap often by two or more fluid lines. Therefore, the ability to control the draw-back force and the amount of comestible fluid drawn back by the valve is limited.
The required draw-back force and the resulting amount of drawn comestible fluid can vary greatly from fluid to fluid (often dependent at least in part upon comestible fluid viscosity and other comestible fluid properties). Lack of draw-back control can present problems when the same dispensing system and draw-back valve is employed to dispense different types of comestible fluids. Problems include drawing in air with the comestible fluid using too much drawing force from the draw-back valve and not providing sufficient force to draw comestible fluid back into the tap or nozzle.
In light of the problems and limitations of the prior art described above, a need exists for a comestible fluid dispensing apparatus, tap, and method which is well-suited for dispensing different types of comestible fluids, reduces or preferably eliminates comestible fluid buildup and dangling comestible fluid from nozzles and taps, prevents dripping, reduces exposure of comestible fluid to the environment between dispenses, is relatively simple in construction, assembly, and maintenance, is inexpensive and adds little to no cost to a conventional comestible fluid dispensing system or tap, and permits increased control over comestible fluid draw-back. Each preferred embodiment of the present invention achieves one or more of these results.
In one preferred embodiment of the present invention, the dispensing apparatus includes a pump operable to pump comestible fluid from a comestible fluid source to a tap provided with a draw-back valve. In some embodiments, the pump can be manually operated or can be powered by a motor or other conventional driving device, while other embodiments do not employ a pump but instead control the flow of comestible fluid under pressure to the tap. In the latter embodiments, flow to the tap can be controlled by an upstream valve.
The tap of the present invention is preferably provided with a draw-back valve capable of drawing comestible fluid in an upstream direction in the tap. Preferably, suction generated by closure of the draw-back valve is employed for one or more purposes including: to remove any comestible fluid dangling from the tap, to draw comestible fluid into the tap away from view and from exposure to the environment, to reduce comestible fluid buildup on and near the tap outlet, to enclose or at least partially enclose comestible fluid downstream of the draw-back valve, and to operate a downstream cutoff valve in the tap.
The draw-back valve is preferably a plunger valve, although other types of valves known in the art can generate sufficient suction force to perform the functions just described. The draw-back valve is movable between opened and closed positions, and more preferably is movable between at least one open position and a range of closed positions. As used herein and in the appended claims the term xe2x80x9cvalvexe2x80x9d refers to that element or mechanism that is movable to enable and stop fluid flow out of the tap in different positions of the valve. For example, the draw-back valve in some preferred embodiments is a plunger valve as mentioned above. In such cases, the plunger valve refers to the plunger itself, and not to the passage through which the plunger moves or the seat (if any) against which the plunger stops when fully closed.
Some highly preferred embodiments employ a draw-back valve that moves through a passage having a substantially constant cross sectional area, a cross sectional area that increases in the downstream direction, or a passage having a portion with a substantially constant cross sectional area and a portion having an increasing cross sectional area in the downstream direction. The draw-back valve need not move fully through the passage (or passage portions), but moves sufficiently to produce the suction force described above. The size of the passage with respect to the draw-back valve, the shape of the passage and passage portions, the distance the draw-back valve moves in the passage (or passage portions), and the speed at which the draw-back valve moves are preferably selected to provide the desired suction force.
In one highly preferred embodiment, the closing draw-back valve moves first at least partially through a passage portion having a passage portion having an increasing cross sectional area in the downstream direction and then through a passage portion having a substantially constant cross sectional area. The valve is preferably sized to match the size of the passage portion having the substantially constant cross sectional area, and more preferably has a sliding seal with the walls of this passage portion. Other embodiments have a clearance between the walls of this passage portion and the valve. The amount of clearance (if any) is preferably dependent at least partially upon the type of comestible fluid being dispensed and the desired amount of suction force downstream of the valve.
The walls of the passage portion having an increasing cross sectional area in the downstream direction can be selected so that suction force is generated when the drawback valve moves through this passage portion. Otherwise, these walls can be shaped so that suction force is primarily generated only when the valve moves through the passage portion having a substantially constant cross sectional area.
Any combination of passage portions with any desired shape and in any desired order (with respect to draw-back valve movement) can be employed, each preferably having at least one portion in which suction force is generated when the draw-back valve moves therethrough when closing.
Some preferred embodiments of the tap employ a shield near the tap outlet (downstream of the draw-back valve if used). This shield can comprise a wall that is preferably apertured to permit passage of comestible fluid therethrough, and can be made of a resilient relatively non-deformable or deformable material. The shield is preferably movable in the tap either by being deformable under comestible fluid pressure upstream of the shield or by being connected within the tap to shift or slide in the tap under such pressure. In either case, pressure changes upstream of the shield preferably generate some type of movement of the shield. This movement in either an upstream or downstream direction preferably dislodges comestible fluid that may be dangling from the tap, the downstream face of the shield, or a nozzle defining the tap outlet.
In some highly preferred embodiments, the shield is part of a cutoff valve which also has a cutoff valve seat located in the tap adjacent to the shield. Preferably, the shield is biased (inherently by its structure or by one or more biasing elements) into a closed position in which the aperture in the shield is plugged by the cutoff valve seat. The shield can be assisted to this position by suction generated by the draw-back valve during closing, in which case a reduced pressure can be maintained between the draw-back and cutoff valves. This reduced pressure helps to prevent opening of the cutoff valve between dispenses, either from the weight of upstream comestible fluid or from shock, jostling, or other movement of the tap.
By employing a cutoff valve as just described, comestible fluid which has not yet exited the tap or which has been drawn back into the tap by the draw-back valve can be retained in a sealed or substantially sealed portion of the tap. This comestible fluid is therefore protected from the tap environment and is less susceptible to drying or spoilage. Although the cutoff valve need not necessarily be employed with the draw-back valve, the two valves can be used together to draw leftover comestible fluid back into the tap through the cutoff valve, to then close or substantially close this comestible fluid in the tap, and to dislodge any other leftover comestible fluid from the outlet, nozzle, and/or cutoff valve.
The draw-back valve of the present invention is preferably biased toward a closed position by one or more springs or other conventional biasing elements or mechanisms. To control movement of and/or bias the draw-back valve, the draw-back valve can be connected to a movable wall which defines part of a chamber in the tap. The movable wall is preferably a damper which is sized to provide a sliding seal within the walls of the tap, to provide resistance to movement by frictional contact with these walls, or to perform both of these functions. Therefore, the damper preferably dampens and controls valve movement and can bias the valve toward a closed position by the reduced pressure in the chamber when the damper is moved with the valve to enlarge the chamber.
It should be noted that the present invention can be used to dispense any comestible fluid that can flow under pressure or otherwise. By way of example only, such comestible fluids include water, soda, beer, juices and other drinks, ketchup, mayonnaise, mustard, relish, sauce, syrup, dressing, and other condiments, soup, dough, filling, icing, and other food products, and the like.
The draw-back valve and the tap valve are preferably the same in the present invention. Therefore, one-tap valve in the present invention performs the same functions as two valves in conventional systems. In addition, the draw-back valve is part of the tap and is not an additional part that must be connected within the dispensing system upstream of the tap. Because the draw-back valve is in or part of the tap and is therefore preferably located relatively close to the tap outlet, better draw-back control is possible (as opposed to draw-back valves located a distance upstream of tap). Also, the tap of the present invention can readily by employed with existing comestible fluid dispensing systems. The draw-back valve of the present invention is easy to assemble, has fewer parts, and is therefore less costly to manufacture and maintain than conventional dispensing systems
Further objects and advantages of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the drawings.